The dramatic event which in 1618 provokes a crisis throughout Europe is known to historians as the Defenestration (out-windowing) of Prague. The windows in question are those of the seat of government, the Hradcany fortified palace. Those forcibly thrown out are two of the regents appointed by the Habsburgs.

Rumour soon embellishes an already dramatic incident, and the drop from the windows to the ground is often described as some fifty feet. It must have been very much less. Both the unfortunate officials survive to play prominent parts in subsequent Bohemian history. But their undignified exit from the palace is a flashpoint in the clash between Catholic rulers and a Protestant majority in Bohemia.

Ferdinand II, crowned king of Bohemia in 1617, has been educated by Jesuits. It is no secret that he intends to impose on his territories the rigorous Catholicism of the Counter-Reformation. Recently his regents in Prague have even tried to instal a Catholic priest in Bethlehem Chapel, forever associated in Protestant minds with the heroic John Huss.

The crisis escalates in 1619 when the Protestant party in Prague declares that the Bohemian crown is elective. They choose as their king one of the few Calvinist princes in the Holy Roman empire, Frederick V of the Rhine Palatinate.

The Winter King: 1619-1620

In accepting the Bohemian throne, and being crowned in Prague in November 1619, Frederick V is perpetrating an extremely inflammatory act within the edgy community of the German states. Ferdinand II, Habsburg successor to the kingdom of Bohemia, has been elected Holy Roman emperor in August of that year.

Frederick owes Ferdinand allegiance, as one of the German princes and as an imperial elector (the elector palatine of the Rhine). Instead, by popular demand in Bohemia, he is usurping his lord's place.

Ferdinand is able to organize a powerful army against the Protestant upstart. The bulk of it comes from the duchy of Bavaria, a Catholic line of the Wittelsbach dynasty and deeply hostile to the Protestant branch headed by Frederick in the Palatinate. In return for his support the Bavarian duke, Maximilian I, is promised Frederick's hereditary lands and his status as an imperial elector.

Frederick, by contrast, receives messages of goodwill but little practical help from the Protestant states.

The issue is decided in a single brief encounter. The Bavarian army, under its distinguished general Johann Tserclaes von Tilly, marches on Prague. A battle at the White Mountain, to the west of the city, lasts only an hour before the Protestant army gives way. On the evening of that same day, 8 November 1620, almost exactly a year after his coronation, Frederick flees from Prague with his family.

His wife is Elizabeth, daughter of James I of England. Their brief reign causes Frederick and Elizabeth to become known as the Winter King and Queen. (But unwittingly they found a dynasty. A century later their grandson becomes king of Great Britain as George I).

After the White Mountain: 1620-1625

Both the emperor Ferdinand II and the duke of Bavaria, Maximilian I, benefit greatly from the victory at the White Mountain.

Ferdinand gains full control over Bohemia. Meanwhile Maximilian has occupied part of Austria, which he intends to hold until all Ferdinand's debts to him are paid. He also now takes much of Frederick's territory in the Palatinate (part has been quietly occupied by the Spanish, moving down from the Netherlands while the locals are busy in Bohemia).

Maximilian is passionately opposed to any increase in Habsburg power. As a great Catholic prince now ruling the whole of southern Germany, he seems well placed to keep Ferdinand in check.

But Ferdinand's ruthless suppression and exploitation of conquered Bohemia introduces a new element to upset the balance. It provides him with great wealth. It also brings to prominence a general and entrepreneur of extraordinary ambition and talent - Albrecht von Wallenstein.

Wallenstein: 1621-1625

With imperial authority re-established in Prague, Ferdinand takes stern measures to end Protestant opposition. Roman Catholicism is the only religion allowed, with all education entrusted to the Jesuits. Some 36,000 Protestant families, of nobles, merchants and craftsmen, emigrate from the kingdom.

The property of those who leave, and of anyone judged to have assisted the rebellion, is expropriated and sold to Ferdinand's supporters. More than 75% of the privately owned land changes hands in this upheaval. No one profits more from the rich available pickings than Albrecht von Wallenstein, whom Ferdinand appoints governor of the kingdom of Bohemia.

Wallenstein is a minor Czech nobleman who becomes rich through marriage to an elderly widow. From 1617 he uses her money to raise a small private army with which he assists Ferdinand. His reward, after the suppression of Bohemia, includes a licence to issue coins debased to half their previous value. With the profit he buys at a knock-down price sixty large estates, which together make him lord of the whole of northeastern Bohemia.

Wallenstein now proposes to Ferdinand a bold extension of his earlier private army. He offers to provide, at no expense to the emperor, an independent imperial army of 24,000 men. The expense, raised by a financial agent, will be recovered from conquered territories.

The idea appeals to Ferdinand because it frees him from reliance on the powerful duke of Bavaria, whose army made possible the victory at the White Mountain. Wallenstein's plan is approved and he is appointed chief of all the imperial forces. Seeing another rich opportunity, he mobilizes his estates in Bohemia to provide arms and equipment for the army.

Wallenstein acquires a welcome opportunity to put his army into the field when Christian IV, the king of Denmark, decides to take a hand in the troubled affairs of Germany.

Lutherans from Scandinavia: 1625-1631

As a Lutheran monarch, the Danish king Christian IV has good cause to support Protestant states in north Germany under threat from Catholic neighbours. He is also eager to keep Catholics away from the Baltic. He has been promised a subsidy by England if he intervenes in Germany's wars. And he is interested in extending his own territory southwards to the estuaries of the Elbe and the Weser.

In May 1625 he marches into Germany.

Christian IV is an unskilled commander, and he has the misfortune to have ranged against him the two most experienced generals of the age. Tilly commands the Bavarian army on behalf of the Catholic League. Wallenstein is at the head of the separate imperial army which he has raised for Ferdinand II.

Christian's first defeat is at the hands of Tilly, at Lutter in August 1626. Between them, Tilly and Wallenstein then drive the Danes north, clearing them from the Baltic coast, pursing them into the peninsula of Denmark and eventually confining Christian IV and his army to the Danish islands.

By 1628 Wallenstein has been granted the duchy of Mecklenburg, and an army of his is besieging the town of Stralsund. If it falls to him, he will be master of the German Baltic coast. This dramatic increase in Catholic power, and in Wallenstein's personal standing, has several results of great significance for the next stage of the war.

A new surge of confidence causes Ferdinand II, in March 1629, to issue the Edict of Restitution. It demands that all Protestant land not specifically ceded in 1555 in the peace of Augsburg be now returned to the Catholic church. This unilateral attempt to put the clock back eighty years is guaranteed to inflame the present religious conflict.

The new Catholic presence on the shores of the previously Lutheran southern Baltic persuades the king of Sweden, Gustavus II, that he should enter the war. Resolving his long dispute with Poland (in the treaty of Altmark in September 1629), he brings an army across the sea and marches into Germany in July 1630.

Meanwhile the greatly increased stature of Wallenstein prompts the duke of Bavaria and the Catholic League to issue an ultimatum. Unless Ferdinand dismisses his general, he can expect no further cooperation. With reluctance, in August 1630, the emperor deprives an outraged Wallenstein of his high command.

After Wallenstein's dismissal, Tilly becomes commander of the combined armies of the Catholic League and of the emperor against the intruding Swedes.

For a year the two opposing sides, Protestant and Catholic, fail to meet in direct battle. Each attempts to secure firm alliances among the many German principalities (Protestant princes are at this stage reluctant to commit themselves to the Swedish king). But eventually, at Breitenfeld near Leipzig in September 1631, there is a confrontation. It is Tilly's misfortune that this is the first public display of new tactics devised by Gustavus II. They prove devastating.

Breitenfeld and Lützen: 1631-1632

The Swedish victory at Breitenfeld causes many of the German Protestant princes to declare their support for Gustavus, who presses his campaign further south into Catholic Germany. In May 1632 he takes Munich. In the same month his ally the Protestant elector of Saxony enters Prague.

Confronted by these threats, the emperor Ferdinand II has already reappointed Wallenstein to his post as commander of the imperial army. Wallenstein's subtle strategies manoeuvre Gustavus out of his newly won territories in the south without risking a pitched battle. When this comes, it is again in the north near Leipzig - at Lützen in November 1632.

Swedish tactics again win the day at Lützen, though Gustavus himself dies leading a cavalry charge. Swedish armies continue to campaign in Germany. But the death of the king ends the heady period when there has been a serious possibility of Protestant Sweden playing a major role in German affairs.

Meanwhile the irrepressible Wallenstein is once again building himself an empire, with the help of an army which owes allegiance more to him than to the real emperor. By 1634 Ferdinand II is so exasperated that he authorizes the assassination (by an English captain, Walter Devereux) of his brilliant but over-ambitious commander.

Peace of Prague: 1635

Exhaustion among the German princes now at last makes a compromise possible. The conflict which flared up in Prague in 1618 is resolved, at least in local terms, by a peace agreed in Prague in 1635.

It is the emperor who makes the major concession. Instead of the ownership of church lands being restored to the situation that prevailed in 1555, as demanded by Ferdinand's Edict of Restitution, the date of the agreed status quo is now to be the very recent one of 1627 - reflecting the period immediately before the issue of the edict in 1629. (In 1648, in the peace of Westphalia, there is a final minor change - the relevant year becomes 1624).

If the war had only involved the German states, the agreement at Prague might well have ended it. But it has had from the start a broader theme, with the Spanish Habsburgs giving active support to the emperor, their Austrian cousin. From 1621 Spain has also renewed her war against the United Provinces of the Netherlands. And the Swedes, at war with the emperor and the Catholic League, are not party to the peace of Prague.

Most significant of all, the improvement in Habsburg fortunes alarms the dynasty's greatest enemy, France. During the months before the peace of Prague, Cardinal Richelieu forms alliances with the United Provinces and Sweden. And he declares war on Spain and the Austrian empire.

Final years and the peace of Westphalia: 1635-1648

The active intervention of France, as the ally of Sweden and the United Provinces against imperial Austria and Spain, ensures that warfare rumbles on for several more years after the peace of Prague in 1635. But it does so in a somewhat haphazard manner, with numerous local encounters across Europe from the Netherlands to Bohemia and with no clear outcome.

There are certain significant turning points. In 1640 Portugal seizes the opportunity to reassert its independence, thus diverting Spain from her efforts to recover the United Provinces. A new northern war adds urgency from 1643, when the Swedes attack Denmark.

By 1643 all sides are eager for a settlement. In July of that year delegates to a peace congress gather in the Westphalian towns of Münster and Osnabrück.

Eventually there are 150 such delegates(all but forty of them German), representing the various interested parties. Their deliberations, spread over five years, are complicated by the fact that warfare is continuing - so the situation over which they are bargaining is in a state of constant flux. Apart from that unusual element, this is the first example of a modern peace conference.

By 1648 major decisions have been agreed, involving both redistribution of territory and the acknowledgement of newly independent states. In territorial terms the main winners from the peace of Westphalia are Sweden (gaining valuable Baltic territory, much of it from Denmark) and France (receiving from the Habsburg empire various rights in Lorraine and Alsace). The Rhine Palatinate is restored to the heir of Frederick V.

Outside Germany the independence of the United Provinces is at last accepted by Spain, and that of the Swiss Confederation is now formally acknowledged (having been recognized in effect since the peace of Basel in 1499).

The most significant concessions are those over which the series of wars has primarily been fought. The Holy Roman emperor (by now Ferdinand III) no longer claims to be the ruler of the German principalities. They are recognized as independent states with the right to engage in their own international diplomacy.

Their future struggles will be not against the anachronistic Holy Roman emperor but among themselves, to discover which of the great German princely dynasties eventually has the strength to assert a new form of leadership within Germany.

On the religious issue, rulers may still (as agreed in the Peace of Augsburg) choose the religion of their own territory, but freedom of conscience is also assured - citizens professing another form of Christianity now have the right to worship in private or to emigrate. An exception to this is one of the few points gained by the emperor; he alone may impose Roman Catholicism on his subjects (though he too makes exceptions, as in the case of Protestant Silesia).

In international terms the effect of all this is a weakened empire, a strengthened France (which does not finally make peace with Spain until 1659), and a fully independent Dutch republic now free to concentrate on its enormously successful commercial and imperial enterprises.